The variation of OER with dose rate

The oxygen enhancement ratio (OER) has been measured as a function of dose rate from 276 Gy/hr to 0.89 Gy/hr for V-79 cells irradiated at 23 degrees C or 37 degrees C. As dose rate is decreased, the OER initially increases, from a value of 3.0, to a maximum value of 3.7 to 4.0, at a dose rate between 20 and 60 Gy/hr. The OER subsequently decreases with further dose rate reduction to a minimum value of 2.4 at the lowest dose rate. Similar experiments conducted with cells in nutrient deprived conditions exhibited a monotonic decrease in OER from 3.0 to 1.7 with dose rate reduction. These experimental findings can be understood in terms of the sublethal damage repair capability of cells under different pO2 and nutrient conditions.     

Carcinoma of the hypopharynx

The data in this study suggest that radical surgical treatment offers the best chance for control of disease in patients with cancer of the hypopharynx. The cervical lymph nodes are at a very high risk for early involvement by metastatic disease. Elective treatment of cervical lymph nodes must be considered in initial treatment planning to obtain better control of regional disease.     

Variables predicting distant metastases in thyroid cancer

OBJECTIVES: Distant metastases from thyroid cancer are uncommon and have a variable prognosis. We present a series of patients with distant metastases to determine which patients are at risk of developing distant disease and to examine the significant prognostic variables. STUDY DESIGN: Retrospective chart review of 30 patients with distant metastases compared with 633 controls from the Mount Sinai Thyroid Cancer Database and literature review. METHODS: The prevalence of distant metastases was 4.5%, and median follow-up of survivors was 12.7 years. Histologic type was Hurthle cell carcinoma in 3, follicular in 3, papillary in 19, and 5 patients had focal anaplasia either in the primary site or regional metastases. Predictors for distant metastases, locoregional control, and survival were analyzed. RESULTS: Cumulative survival for patients with distant metastases was 49.5% at 10 years and 12.9% at 20 years. Site of metastases was lung in 26, bone in 11 and brain in 1 patient, with 8 patients having multiple sites. The median time to diagnosis of distant metastases was 3 months. Variables that predicted for development of distant disease were male sex, age, size, extrathyroidal extension, regional metastases, and elevated thyroglobulin. Survival in patients without distant disease was significantly better than those with distant metastases (P < .001). Variables that predicted poor outcome in patients with distant metastases on analysis were age greater than 45 years (P = .003) and histologic type of thyroid cancer (P = .009). CONCLUSION: Although patients with thyroid cancer and distant metastases may live prolonged periods with disease, it does significantly impact on patient survival. Age remains an important variable in both predicting for development of distant metastases and also influences long-term survival in patients with existing distant metastases.